1. Field of the Invention
The present invention relates to an electron emission apparatus provided with an electron beam source plate and a light emitting plate placed face to face.
2. Discussion of Related Art
Generally, an electron emission device is classified as a hot or cold cathode type, wherein the hot cathode type and the cold cathode type respectively employ a hot cathode and a cold cathode as an electron emission source. A cold cathode type electron emission device includes a structure such as a field emitter array (FEA), a surface conduction emitter (SCE), a metal insulating layer metal (MIM), a metal insulating layer semiconductor (MIS), and a ballistic electron surface emitter (BSE).
The electron emission device having the FEA structure is based on a principle that a material having a low work function and a high β-function easily emits electrons in a vacuum in response to an electric field difference, thereby operating as an electron emission source. Such an electron emission device having the FEA structure has been developed, which uses a tip structure, a carbon material, or a nano material as the electron emission source.
The electron emission device having the SCE structure includes an electron emission part, which has a conductive layer placed on a plate between two electrodes opposite each other and formed with a minute crack or gap, thereby forming the electron emission part. Such an electron emission device is based on a principle that the electron emission part formed by a minute crack or gap emits electrons when electric current due to a voltage applied between two electrodes flows through the surface of the conductive layer.
The electron emission device having an MIM or MIS structure includes an electron emission source having a metal-insulator-metal structure or a metal-insulator-semiconductor structure, and is based on a principle that electrons are moved and accelerated from a metal or semiconductor of high electric potential to a metal of low electric potential when a voltage is applied between the metal and the metal or between the metal and the semiconductor, respectively, thereby emitting electrons.
The electron emission device having the BSE structure is based on a principle that electrons travel without sputtering when the size of a semiconductor is smaller than a mean free path of the electrons contained in the semiconductor. Such an electron emission device includes an electron supplying layer made of a metal or a semiconductor and formed on an ohmic electrode, an insulator formed on the electron supplying layer, and a thin metal layer formed on the insulator, so that electrons are emitted when a voltage is applied between the ohmic electrode and the thin metal layer.
The above-referenced electron emission devices are employed in an electron emission apparatus, various backlights, and a lithography electron beam, etc. The electron emission apparatus includes an electron emission part provided with the electron emission device to emit electrons, and a light emission region in which the emitted electrons collide with a fluorescent material to emit light. Generally, the electron emission apparatus includes a plurality of electron emission devices formed on a first plate; and a fluorescent layer formed on a second plate and colliding with the electrons emitted from the first plate.
Further, in the electron emission apparatus, a supporting member is provided between the first plate and the second plate.
However, in the conventional electron emission apparatus, some electrons emitted from the electron emission part may collide not with a corresponding sub-pixel but with other sub-pixel, or may not collide with the fluorescent layer but with a surface of the supporting member and be thus charged in the supporting member. The charged supporting member deflects the electrons emitted from the electron emission part and traveling toward the fluorescent layer. Further, when the supporting member is charged by a predetermined quantity of electric charge or more, the electric charge may bolt out of the supporting member, thereby generating an arc.